This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-013654, filed Jan. 22, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a silver halide photographic emulsion used for a silver halide photographic lightsensitive material. More specifically, the present invention relates to a high-sensitive and high-gamma silver halide photographic emulsion. On the other hand, the present invention relates to a silver halide photographic emulsion being excellent in graininess, easy to impart an inter image effect and subject to it when it is used for a silver halide color reversal lightsensitive material.
2. Description of the Related Art
It has been well known to use tabular silver halide grains (hereinafter, referred to as xe2x80x9ctabular grainsxe2x80x9d) in order to obtain a high-sensitive silver halide photographic lightsensitive material. It is also well known that the higher an aspect ratio is, the more remarkable the high-sensitization effect is.
On the other hand, a method of increasing sensitivity by making denser a dislocation line introduction to fringe portions of tabular grains than a dislocation line introduction onto the principal surfaces of tabular grains is disclosed in U.S. Pat. No. 5,709,988. However, although this method can attain high sensitization and high gamma-making to a certain degree, there has been a problem that a high aspect-making and a dislocation density are not compatible. Namely, it has been an actual circumstance that the aspect ratio is lowered when the dislocation is densely introduced. This has been remarkable in a territory in which grain sizes are small in particular (e.g., an equivalent-circle diameter of 0.5 xcexcm or less).
An technique of improving a sensitivity/grain ratio by multiple-structure tabular grain emulsion having a quintuple structure or more is disclosed in U.S. Pat. No. 5,780,216. However, there has been a problem that it is hardly subject to the inter image effect when it is used for a silver halide color reversal lightsensitive material, because the silver iodide content of the outermost layer shell is high at 15 mol % to 40 mol % in said patent.
It is an object of the present invention to provide a silver halide photographic emulsion which has a comparatively high aspect ratio, attains a high-sensitization and high gamma-making of small-size tabular grains, and is excellent in graininess and an inter image effect in case of being used for a color reversal lightsensitive material; and a photographic lightsensitive material using thereof.
The above-mentioned objects were attained by the following means (1) to (9).
(1) A silver halide photographic emulsion wherein a variation coefficient of an equivalent-circle diameter of all the silver halide grains is 40% or less, and 50% or more of the total projected area is occupied by tabular grains satisfying requirements (i) to (v):
(i) silver iodobromide having (111) faces as principal surfaces;
(ii) the equivalent-sphere diameter of 0.5 xcexcm or less, a thickness of 0.20 xcexcm or less, and an average aspect ratio of 3 or more;
(iii) a silver iodide content of 2 mol % or more and 6 mol % or less;
(iv) a multiple-structure having a quintuple structure or more in which a silver iodide distribution has at least two maximums from a center to an edge, the first maximum is in a range of 3 to 25% by a silver amount constituting grains, and the second maximum is in a range of 50 to 80%; and
(v) ten or more of dislocation lines per grain are present at a fringe portion.
(2) The silver halide photographic emulsion according to item (1), wherein a relation of 0.95It greater than Is is satisfied when an average silver iodide content of each grain is defined as It and an average silver iodide content in the grain surface is defined as Is.
(3) The silver halide photographic emulsion according to item (1) or (2), wherein at least a portion of silver halide grains has a positive hole-capturing zone.
(4) The silver halide photographic emulsion according to any one of items (1) to (3), wherein an electron-capturing dopant having a shallow capturing level is doped in at least one portion of silver halide grains.
(5) The silver halide photographic emulsion according to any one of items (1) to (4), wherein the variation coefficient of the equivalent-circle diameter of all the grains is 25% or less.
(6) The silver halide photographic emulsion according to any one of items (1) to (5), which is spectrally sensitized by a spectral sensitizing dye.
(7) The silver halide photographic emulsion according to any one of items (1) to (6), which is selenium-sensitized and contains at least one water-soluble mercaptotetrazole compound represented by formula (I-1) and at least one water-soluble mercaptotriazole compound represented by formula (I-2): 
Where R5 represents an organic residual group substituted with at least one selected from the group consisting of xe2x80x94SO3M, xe2x80x94COOM, xe2x80x94OH and xe2x80x94NHR2; M represents a hydrogen atom, an alkali metal atom, a quaternary ammonium group or a quaternary phosphonium group; R2 represents a hydrogen atom, an alkyl having 1 to 6 carbon atoms, xe2x80x94COR3, xe2x80x94COOR3 or xe2x80x94SO2R3; and R3 represents a hydrogen atom, an alkyl, or an aryl. 
Where R5 and M have the same meaning as those in general formula (I-1). R6 represents a hydrogen atom, a substituted or unsubstituted alkyl, or a substituted or unsubstituted aryl.
(8) A silver halide photographic lightsensitive material having at least one lightsensitive silver halide emulsion layer on a support and containing the silver halide photographic emulsion according to any one of items (1) to (7) in the lightsensitive silver halide emulsion layer.
(9) A silver halide color reversal photographic lightsensitive material having at least one lightsensitive silver halide emulsion layer on a support and containing the silver halide photographic emulsion according to any one of items (1) to (7) in the lightsensitive silver halide emulsion layer.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.